The use of plastic bags to contain blood has been common for many years. Blood is also centrifuged in such bags to separate plasma, red blood cells, and white blood cells. Plasma is the non-cellular component of blood. Useful plasma for medical purposes must be platelet-rich and void of red blood cells and white blood cells.
Plastic bags used for this purpose typically comprise two sheets of heavy plastic which have been sealed together at their edges. At the top edge of the bag there is a flap formed by the two sheets being sealed together. Typically there is a port or opening at the top of the bag which communicates with the interior cavity of the bag. The port normally appears as a cylindrical, tubular member to which an elongated flexible tube is normally attached. A clamp is used to close the tube. Normally there are two spaced apertures which extend through the flap at the top edge of the bag. The apertures facilitate hanging of the bag on a holder.
Various means have been previously proposed for holding a plastic blood bag in a centrifuge. For example, a cylindrical cup-shaped member has been proposed in which the blood bag is simply inserted into the cup in a manner such that the top of the bag is at the top of the cup. However, the cup-shaped member does not include any means to assure that the top of the bag will not become folded during centrifuging and thereby entrap a portion of the whole blood. Also, any folds in the bag itself can entrap portions of the whole blood. As a result, the red blood cells in the trapped portions of the whole blood are prevented from becoming separated from the plasma during centrifuging since when the bag is removed from the centrifuge the trapped portions of the blood are freed and become mixed with the plasma. However, unless essentially all of the red blood cells are separated from the plasma, the plasma is medically unacceptable.
Although it has also been proposed to use an oval-shaped cup to hold the bag in the centrifuge so as to reduce the possibility of the blood bag rupturing during centrifuging. However, the use of such a holder increases the difficulty of removing the blood bag from the holder after centrifuging. As a result, disturbance of the red blood cells can occur, causing intermixing of red blood cells and plasma
To overcome some of the foregoing problems there has been proposed a blood bag port support comprising a metal stand having a circular base section and an upper portion which includes two hooks to engage the upper edge of the blood bag while the blood bag is in the cup holder in a centrifuge. This type of port support, however, is unbalanced since it is asymmetrical. As a result, the centrifuge cup tips because of the heavier weight on one side of the cup. Thus, the bag is not aligned with the centrifugal force. Consequently, mixing or vortexing within the blood bag during centrifuging can occur, which results in red blood cells mixing with the plasma, and the plasma is not sufficiently platelet-rich. Yet another disadvantage of this type of holder is that the contents of the blood bag maybe disturbed when the bag is disconnected from the hooks of the holder after centrifuging, thus causing red blood cells to mix with the plasma. Also, different holders may be required for different types of bags.
Yet another type of blood bag holder is described in U.S. Pat. No. 3,830,425 which comprises a U-shaped member made of spring steel. The free ends of the U are adapted to be drawn together to secure the mouth of a blood bag which has been inerted therein. Clamps are then applied to the free ends to hold them tightly together. The holder, with the bag securely clamped in place, is then inserted into the centrifuge. However, this type of holder cannot be used with existing centrifuge cups; consequently, special cups must be used. Also, removal of the blood bag from the holder after centrifuging may be difficult to do without mixing of the red blood cells with the plasma. First the clamp must be loosened and removed, then the jaws must be spread and, while the jaws are held apart, the bag must be disengaged from the jaws and slid outwardly in a sideways motion. The greater the manipulation of the bag the greater is the chance of mixing the interface of the red blood cells and the plasma. With the advent of pilot bags containing nutritive additives, it would be necessary to have a larger cup and holder to serve the original purpose. Nutritive additives in pilot bags increase the total volume of the blood bag conglomeration by nearly 25%. This larger volume could not easily be accommodated, if at all, by the original holder-cup arrangement. Furthermore, different holders would be necessary for different types of blood bags.
There has not heretofore been provided a blood bag support system having the advantages inherent in the system of the present invention.